Influence of (Nd+Y)/Al ratio on sintering behavior and optical features of Y3-xNdxAl5O12 ceramics for laser applications

In this study, Nd:YAG ceramics with different (Nd+Y)/Al ratios around the stoichiometric one ((Nd+Y)/Al = 0.6000) with high accuracy (better than 0.1%) were elaborated by solid-state reactive-sintering under vacuum. The influence of (Nd+Y)/Al ratio on sintering behavior, microstructural and optical properties of as-obtained ceramics were systematically studied. This study shows that Al-excess strongly promotes mass transfer by diffusion, and consequently, densification and grain growth processes whereas Y-excess lead to opposite behavior. Results were interpreted by considering several parameters such as local chemical composition, intrinsic/extrinsic crystalline defects, and interactions between pores, secondary phases and grain boundaries. Finally, exact stoichiometry or Y-excess appear to be more favorable to obtain highly transparent Nd:YAG ceramics suitable for laser operation.